Titanium-doped indium oxide films

ABSTRACT

An apparatus and methods of forming the apparatus include a film of transparent conductive titanium-doped indium oxide for use in a variety of configurations and systems. The film of transparent conductive titanium-doped indium oxide may be structured as one or more monolayers. The film of transparent conductive titanium-doped indium oxide may be formed using atomic layer deposition.

RELATED APPLICATIONS

This application is a Continuation Application of U.S. application Ser.No. 12/551,023, filed on 31 Aug. 2009, now U.S. Pat. No. 8,273,177 whichis a Continuation Application of U.S. application Ser. No. 11/400,836,filed 7 Apr. 2006, now issued as U.S. Pat. No. 7,582,161, which areincorporated herein by reference in their entirety.

TECHNICAL FIELD

This application relates generally to devices having a transparentconductive oxide film and fabrication of such devices.

BACKGROUND

Transparent conductive oxide (TCO) materials are components in a varietyof devices including flat-panel displays, photovoltaic cells, smartwindows, light emitting diodes, and optical waveguides. The performanceof a TCO may be related both to the conductivity of the TCO and to theoptical transparency of the TCO. According to the Drude model,conductivity is related to the carrier concentration and the mobility ofthe carrier. However, with increased carrier concentration in amaterial, there may be decrease in optical transparency. To increaseconductivity without decreasing optical transparency, the carriermobility in a material should be increased without increasing carrierconcentration.

Currently, tin-doped indium oxide (ITO) is a transparent conductiveoxide material for commercial applications. ITO has good opticalproperties and good electrical properties. Another material that hasbeen considered is indium oxide doped with molybdenum. Using Mo-dopedindium oxide can provide a TCO material that has a high carrier mobilityof about 70 cm²V⁻¹s⁻¹. Combinatorial deposition and analyticaltechniques have been applied to sputtered films of In₂O₃ doped withtitanium up to 7 atomic percent concentration. These sputtered filmswere determined to have a maximum mobility of 83.3 cm²V⁻¹s⁻¹ at atitanium doping of 1.7 atomic percent and a conductivity of 6260 Ω⁻¹cm⁻¹for titanium doping of 2.8 atomic percent. The optical transparency forthese sputtered Ti-doped indium oxide films has been measured to begreater than 85% over a wide spectral range. In addition, for theseTi-doped indium oxide films with titanium doping concentrations between1 and 3 atomic percent, one carrier is generated for every titaniumatom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a block diagram of an embodiment of a flat paneldisplay having a transparent conductive titanium-doped indium oxide filmas a transparent conductive oxide layer.

FIG. 1B shows a circuit diagram of an embodiment representative of theflat panel display of FIG. 1A.

FIG. 1C shows a representation of an energy diagram of an embodiment ofthe flat panel display of FIG. 1A.

FIG. 2 illustrates a representation of an embodiment of an apparatushaving a photovoltaic cell contacting a transparent conductivetitanium-doped indium oxide film as a front-side transparent conductiveoxide layer.

FIG. 3A illustrates a representation of a cross sectional view of alight emitting diode having a transparent conductive titanium-dopedindium oxide film as a transparent conductive oxide contact.

FIG. 3B illustrates a representation of a top view of the light emittingdiode on a semiconductor surface of FIG. 3A.

FIG. 4 shows a representation of an embodiment of a transparentconductive titanium-doped indium oxide film as a low emissivitytransparent conductive oxide layer of a smart window.

FIG. 5 shows a representation of an embodiment of a transparentconductive titanium-doped indium oxide film as a transparent conductiveoxide layer to heat a smart window.

FIG. 6 depicts a representation of an embodiment of a transparentconductive titanium-doped indium oxide film as a transparent conductiveoxide layer for an optical waveguide structure.

FIG. 7 depicts a representation of an embodiment of a transparentconductive titanium-doped indium oxide film as a transparent conductiveoxide layer for an optical waveguide structure.

FIG. 8 depicts a representation of an embodiment of an apparatus havinga transparent conductive titanium-doped indium oxide film as atransparent conductive oxide layer to provide electrooptic modulation.

FIG. 9 illustrates a block diagram for a system having one or moredevices having a structure including a transparent conductivetitanium-doped indium oxide film.

FIG. 10 shows a block diagram of an embodiment of a system having acontroller coupled to various devices, in which at least one devicecontains a transparent conductive titanium-doped indium oxide film.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawingsthat show, by way of illustration, embodiments in which the presentinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thepresent invention. Other embodiments may be utilized and structural,logical, and electrical changes may be made without departing from thescope of the present invention. The various embodiments are notnecessarily mutually exclusive, as some embodiments can be combined withone or more other embodiments to form new embodiments.

The term substrate used in the following description includes anystructure having an exposed surface with which to form a structure,e.g., an integrated circuit (IC) structure. The term substrate may alsobe used to refer to structures during processing, and may include otherlayers that have been fabricated thereupon. A substrate may includedoped and undoped semiconductors, epitaxial semiconductor layerssupported by a base semiconductor or insulator, as well as othersemiconductor structures well known to one skilled in the art. The termconductor is understood to generally include n-type and p-typesemiconductors and the term insulator or dielectric is defined toinclude any material that is less electrically conductive than thematerials referred to as conductors. The following detailed descriptionis, therefore, not to be taken in a limiting sense.

In an embodiment, a titanium-doped indium oxide film may be formed usingatomic layer deposition (ALD). In an embodiment, a method includesforming a film of titanium-doped indium oxide using ALD to form atransparent conductive oxide film. Embodiments include structures andmethods to form such structures for flat-panel displays, photovoltaiccells, smart windows, light emitting diodes, optical waveguides, andother apparatus containing a titanium-doped indium oxide layerstructured as one or more monolayers. Forming such structures usingatomic layer deposition may allow control of transitions betweenmaterial layers. As a result of such control, atomic layer depositedtitanium-doped indium oxide films may have an engineered transition witha substrate surface on which it is deposited. Constructingtitanium-doped indium oxide films using ALD provides transparentconductive oxide films having a mobility to increase electricalconductivity without sacrificing optical transparency.

ALD, also known as atomic layer epitaxy (ALE), is a modification ofchemical vapor deposition (CVD) and is also called “alternativelypulsed-CVD.” In ALD, gaseous precursors are introduced one at a time tothe substrate surface mounted within a reaction chamber (or reactor).This introduction of the gaseous precursors takes the form of pulses ofeach gaseous precursor. In a pulse of a precursor gas, the precursor gasis made to flow into a specific area or region for a short period oftime. Between the pulses, the reaction chamber may be purged with a gas,where the purging gas may be an inert gas. Between the pulses, thereaction chamber may be evacuated. Between the pulses, the reactionchamber may be purged with a gas and evacuated.

In a chemisorption-saturated ALD (CS-ALD) process, during the firstpulsing phase, reaction with the substrate occurs with the precursorsaturatively chemisorbed at the substrate surface. Subsequent pulsingwith a purging gas removes precursor excess from the reaction chamber.

The second pulsing phase introduces another precursor on the substratewhere the growth reaction of the desired film takes place. Subsequent tothe film growth reaction, reaction byproducts and precursor excess arepurged from the reaction chamber. With favourable precursor chemistrywhere the precursors adsorb and react with each other aggressively onthe substrate, one ALD cycle can be performed in less than one second inproperly designed flow type reaction chambers. Typically, precursorpulse times range from about 0.5 sec to about 2 to 3 seconds. Pulsetimes for purging gases may be significantly longer, for example, pulsetimes of about 5 to about 30 seconds.

In ALD, the saturation of all the reaction and purging phases makes thegrowth self-limiting. This self-limiting growth results in large areauniformity and conformality, which has important applications for suchcases as planar substrates, deep trenches, and in the processing ofporous silicon and high surface area silica and alumina powders. Atomiclayer deposition provides control of film thickness in a straightforwardmanner by controlling the number of growth cycles.

The precursors used in an ALD process may be gaseous, liquid or solid.However, liquid or solid precursors should be volatile. The vaporpressure should be high enough for effective mass transportation. Also,solid and some liquid precursors may need to be heated inside thereaction chamber and introduced through heated tubes to the substrates.The necessary vapor pressure should be reached at a temperature belowthe substrate temperature to avoid the condensation of the precursors onthe substrate. Due to the self-limiting growth mechanisms of ALD,relatively low vapor pressure solid precursors can be used, thoughevaporation rates may vary somewhat during the process because ofchanges in their surface area.

There are several other characteristics for precursors used in ALD. Theprecursors should be thermally stable at the substrate temperature,because their decomposition may destroy the surface control andaccordingly the advantages of the ALD method that relies on the reactionof the precursor at the substrate surface. A slight decomposition, ifslow compared to the ALD growth, may be tolerated.

The precursors should chemisorb on or react with the surface, though theinteraction between the precursor and the surface as well as themechanism for the adsorption is different for different precursors. Themolecules at the substrate surface should react aggressively with thesecond precursor to form the desired solid film. Additionally,precursors should not react with the film to cause etching, andprecursors should not dissolve in the film. Using highly reactiveprecursors in ALD contrasts with the selection of precursors forconventional CVD.

The by-products in the reaction should be gaseous in order to allowtheir easy removal from the reaction chamber. Further, the by-productsshould not react or adsorb on the surface.

In a reaction sequence ALD (RS-ALD) process, the self-limiting processsequence involves sequential surface chemical reactions. RS-ALD relieson chemistry between a reactive surface and a reactive molecularprecursor. In an RS-ALD process, molecular precursors are pulsed intothe ALD reaction chamber separately. A metal precursor reaction at thesubstrate is typically followed by an inert gas pulse to remove excessprecursor and by-products from the reaction chamber prior to pulsing thenext precursor of the fabrication sequence.

By RS-ALD, films can be layered in equal metered sequences that may allbe identical in chemical kinetics, deposition per cycle, composition,and thickness. RS-ALD sequences generally deposit less than a full layerper cycle. Typically, a deposition or growth rate of about 0.25 to about2.00 Å per RS-ALD cycle may be realized.

Processing by RS-ALD provides continuity at an interface avoiding poorlydefined nucleating regions that are typical for chemical vapordeposition (<20 Å) and physical vapor deposition (<50 Å), conformalityover a variety of substrate topologies due to its layer-by-layerdeposition technique, use of low temperature and mildly oxidizingprocesses, lack of dependence on the reaction chamber, growth thicknessdependent solely on the number of cycles performed, and ability toengineer multilayer laminate films with a resolution of one to twomonolayers. RS-ALD processes allow for deposition control on the orderof monolayers and the ability to deposit monolayers of amorphous films.

Herein, a sequence refers to the ALD material formation based on an ALDreaction of a precursor with its reactant precursor. An ALD sequence fora binary metal oxide may be referenced with respect to the metal andoxygen. For example, titanium oxide may be formed using a sequenceincluding a TiCl₄ precursor and water, as its reactant precursor, wheresuch a sequence may be referred to as a titanium/oxygen sequence or atitanium sequence. In various ALD processes that form an oxide or acompound that contains oxygen, a reactant precursor that contains oxygenis used to supply the oxygen. Herein, a precursor that contains oxygenand that supplies oxygen to be incorporated in the ALD compositionformed, which may be used in an ALD process with precursors supplyingthe other elements in the ALD compound, is referred to as an oxygenreactant precursor. With an ALD process using TiCl₄ and water vapor,water vapor is an oxygen reactant precursor. An ALD cycle may includepulsing a precursor, pulsing a purging gas for the precursor, pulsing areactant precursor, and pulsing the reactant precursor's purging gas. AnALD cycle may include pulsing a precursor, evacuating the reactantchamber, pulsing a reactant precursor, and evacuating the reactantchamber. An ALD cycle may include pulsing a precursor, pulsing a purginggas for the precursor and evacuating the reactant chamber, pulsing areactant precursor, and pulsing the reactant precursor's purging gas andevacuating the reactant chamber.

In forming a layer of a metal species, an ALD sequence may deal withpulsing a reactant precursor to the substrate surface on which ametal-containing species has been adsorbed such that the reactantprecursor reacts with the metal-containing species resulting in themetal and a gaseous by-product that can be removed during the subsequentpurging/evacuating process. Alternatively, in forming a layer of a metalspecies, an ALD sequence may deal with reacting a precursor containingthe metal species with a substrate surface. A cycle for such a metalforming sequence may include pulsing a purging gas after pulsing theprecursor containing the metal species to deposit the metal.Additionally, deposition of a semiconductor material may be realized ina manner similar to forming a layer of a metal, given the appropriateprecursors for the semiconductor material.

In an ALD formation of a compound having more than two elements, a cyclemay include a number of sequences to provide the elements of thecompound. For example, a cycle for an ALD formation of an ABO_(x)compound may include sequentially pulsing a first precursor/a purginggas for the first precursor/a first reactant precursor/the firstreactant precursor's purging gas/a second precursor/a purging gas forthe second precursor/a second reactant precursor/the second reactantprecursor's purging gas, which may be viewed as a cycle having twosequences. In an embodiment, a cycle may include a number of sequencesfor element A and a different number of sequences for element B. Theremay be cases in which ALD formation of an ABO_(x) composition uses oneprecursor that contains the elements A and B, such that pulsing the ABcontaining precursor followed by its reactant precursor onto a substratemay include a reaction that forms ABO_(x) on the substrate to provide anAB/oxygen sequence. A cycle of an AB/oxygen sequence may include pulsinga precursor containing A and B, pulsing a purging gas for the precursor,pulsing an oxygen reactant precursor to the A/B precursor, and pulsing apurging gas for the reactant precursor. A cycle may be repeated a numberof times to provide a desired thickness of the composition. In anembodiment, a cycle for an ALD formation of a composition oftitanium-doped indium oxide may include interspersing titanium sequencesamong a number of indium sequences, which may be viewed as a cyclehaving multiple sequences. In an embodiment, a layer substantially of anindium oxide doped with titanium is formed on a substrate mounted in areaction chamber using ALD in repetitive indium/oxygen sequences with alimited number of titanium sequences using precursor gases individuallypulsed into the reaction chamber. Solid or liquid precursors can be usedin an appropriately designed reaction chamber.

In an embodiment, a titanium-doped indium oxide layer may be structuredas one or more monolayers. A film of titanium-doped indium oxide,structured as one or more monolayers, may have a thickness that rangesfrom a monolayer to thousands of angstroms or more. The film may beprocessed using atomic layer deposition.

The term titanium-doped indium oxide is used herein with respect to acomposition that essentially consists of indium and oxygen with alimited amount of titanium. A titanium-doped indium oxide layer is alayer in which the indium oxide may have a form that may be nearstoichiometric, non-stoichiometric, or a combination of nearstoichiometric and non-stoichiometric and has a limited amount oftitanium. Other nomenclature for a composition that essentially consistsof indium and oxygen with a limited amount of titanium may be known tothose skilled in the art. Herein, a titanium-doped indium oxide compoundmay be expressed as Ti-doped InO, Ti-doped InO_(x), or other equivalentform. A transparent conductive Ti-doped InO may be expressed as ITiO orother equivalent form. The expression InO_(x) may be used to include astoichiometric indium oxide. The expression InO_(x) may be used toinclude a non-stoichiometric indium oxide. The expression InO_(x) may beused to include a combination of a stoichiometric indium oxide and anon-stoichiometric indium oxide. The expression TiO_(y) may be used inthe same manner as InO_(x). In various embodiments, a titanium-dopedindium oxide film may be doped with elements or compounds other thantitanium, indium, and oxygen.

In an embodiment, a Ti-doped InO_(x) film may be structured as one ormore monolayers. In an embodiment, the Ti-doped InO_(x) film may beconstructed using atomic layer deposition. Prior to forming the Ti-dopedInO_(x) film using ALD, the surface on which the Ti-doped InO_(x) filmis to be deposited may undergo a preparation stage. The surface may bethe surface of a glass substrate. In other embodiments, silicon,germanium, gallium arsenide, silicon-on-sapphire, silicon oxide,amorphous aluminum oxide, sapphire, or other suitable substrates may beused. In an embodiment, the substrates may be of an appropriate materialin single crystal form. A preparation process may include cleaning thesubstrate and forming layers and regions of the substrate.Alternatively, operational regions may be formed after forming theTi-doped InO_(x) film, depending on the over-all fabrication processimplemented. In an embodiment, the substrate is cleaned to provide aninitial substrate depleted of its native oxide. In an embodiment, theinitial substrate is cleaned also to provide a hydrogen-terminatedsurface. In an embodiment, a substrate undergoes a final hydrofluoric(HF) rinse prior to ALD processing to provide the substrate with ahydrogen-terminated surface without a native oxide layer.

In various embodiments, between each pulsing of a precursor used in anatomic layer deposition process, a purging gas may be pulsed into theALD reaction chamber. Between each pulsing of a precursor, the ALDreactor chamber may be evacuated using vacuum techniques as is known bythose skilled in the art. Between each pulsing of a precursor, a purginggas may be pulsed into the ALD reaction chamber and the ALD reactorchamber may be evacuated.

In an embodiment, layers of titanium oxide formed by atomic layerdeposition may be interspersed among layers of indium oxide that areformed by atomic layer deposition. The titanium oxide and indium oxidelayers may be annealed to form transparent conductive titanium-dopedindium oxide. In an embodiment, the concentration of titanium oxide isless than 7% in the layers of titanium oxide and indium oxide layers tobe annealed. In an embodiment, a transparent conductive film oftitanium-doped indium has a titanium atomic concentration less than orequal to 7%. In an embodiment, a transparent conductive film oftitanium-doped indium has an atomic concentration of titanium rangingfrom 1% to 3%.

To form indium oxide by atomic layer deposition, an indium-containingprecursor is pulsed onto a substrate in an ALD reaction chamber. Anumber of precursors containing indium may be used to provide the indiumto a substrate. In an embodiment, a precursor containing indium mayinclude an indium halide. InCl₃ may be used as a precursor in an indiumsequence. In an embodiment using an InCl₃ precursor, the substratetemperature may be maintained at a temperature of about 500° C. In anembodiment, the InCl₃ precursor may be evaporated from a crucible heldat 285° C. within the ALD system. After pulsing the InCl₃ precursor andpurging the reaction chamber of excess precursor and by-products frompulsing the precursor, a reactant precursor may be pulsed into thereaction chamber. Water vapor may be used as an oxygen reactant and maybe generated in a reservoir held in a tempered bath at 25° C. Inert gasvalving may be used to pulse the InCl₃ precursor while closing out watervapor with a solenoid valve. Use of an InCl₃ precursor and water vaporis not limited to the temperature ranges of the above exampleembodiment. The indium oxide may be formed on a glass substrate. Othermaterials may be used for the substrate depending on the application. Invarious embodiments, after pulsing the indium-containing precursor andpurging the reaction chamber of excess precursor and by-products frompulsing the precursor, a reactant precursor may be pulsed into thereaction chamber. The reactant precursor may be an oxygen reactantprecursor including, but not limited to, one or more of water vapor,atomic oxygen, molecular oxygen, ozone, hydrogen peroxide, awater—hydrogen peroxide mixture, alcohol, or nitrous oxide. In variousembodiments, use of the individual indium-containing precursors is notlimited to the temperature ranges of the above example embodiments.Further, forming indium oxide by atomic layer deposition is not limitedto the abovementioned precursors. In addition, the pulsing of the indiumprecursor may use a pulsing period that provides uniform coverage of amonolayer on the surface or may use a pulsing period that providespartial coverage of a monolayer on the surface during an indiumsequence.

To form titanium oxide by atomic layer deposition, a titanium-containingprecursor is pulsed onto a substrate in an ALD reaction chamber. Anumber of precursors containing titanium may be used to provide thetitanium on the substrate. In an embodiment, the titanium-containingprecursor may be TiCl₄. In an embodiment using a TiCl₄ precursor, thesubstrate temperature may be maintained at a temperature ranging fromabout 100° C. to about 500° C. In an embodiment using a TiCl₄ precursor,the substrate temperature may be maintained at a temperature of about425° C. or higher. In an embodiment, using a TiCl₄ precursor with watervapor as an oxygen reactant in the formation of titanium oxide allowsfor epitaxial growth of rutile. In an embodiment, a titanium precursorpulsed may be TiI₄. In an embodiment using a TiI₄ precursor, thesubstrate temperature may be maintained between about 230° C. and about490° C. A TiI₄ precursor may be used with H₂O₂ as an oxygen reactant toform thin films of epitaxial titanium oxide at relatively lowtemperatures. In an ALD process using TiI₄ and H₂O₂ precursors, bothrutile and anatase phases may be formed. Typically, anatase is formed atlower temperatures. The substrate material may affect the anatase/rutilephase boundary temperature. Phase-pure rutile has been shown to beattainable on a-Al₂O₃ (0 1 2) at temperatures of 275° C. or higher.Phase-pure anatase has been shown to be attainable on MgO (0 0 1) attemperatures of 375° C. or less. In an embodiment, a titanium precursorpulsed may be anhydrous Ti(NO₃)₄. In an embodiment using a Ti(NO₃)₄precursor, the substrate temperature may be maintained at a temperatureranging from less than 250° C. to about 700° C. In an embodiment, atitanium precursor pulsed may be titanium tetraisopropoxide, alsowritten as Ti(O^(i)—Pr)₄. In an embodiment using a Ti(O^(i)—Pr)₄precursor, the substrate temperature may be maintained at a temperatureranging from less than 250° C. to about 325° C. Use of the individualtitanium precursors is not limited to the temperature ranges of theabove embodiments. In various embodiments, after pulsing thetitanium-containing precursor and purging the reaction chamber of excessprecursor and by-products from pulsing the precursor, a reactantprecursor may be pulsed into the reaction chamber. The reactantprecursor may be an oxygen reactant precursor including, but are notlimited to, one or more of water vapor, atomic oxygen, molecular oxygen,ozone, hydrogen peroxide, a water—hydrogen peroxide mixture, alcohol, ornitrous oxide. In addition, the pulsing of the titanium precursor mayuse a pulsing period that provides uniform coverage of a monolayer onthe surface or may use a pulsing period that provides partial coverageof a monolayer on the surface during a titanium sequence.

In various embodiments, nitrogen may be used as a purging gas and acarrier gas for one or more of the sequences. Alternatively, hydrogen,argon gas, or other inert gases may be used as the purging gas. Excessprecursor gas and reaction by-products may be removed by the purge gas.Excess precursor gas and reaction by-products may be removed byevacuation of the reaction chamber using various vacuum techniques.Excess precursor gas and reaction by-products may be removed by thepurge gas and by evacuation of the reaction chamber.

Atomic layer deposition of the individual components or layers ofInO_(x) and TiO_(y) allows for individual control of each precursorpulsed into the reaction chamber. Thus, each precursor is pulsed intothe reaction chamber for a predetermined period, where the predeterminedperiod can be set separately for each precursor. Additionally, forvarious ALD formations, each precursor may be pulsed into the reactionchamber under separate environmental conditions. The substrate may bemaintained at a selected temperature and the reaction chamber maintainedat a selected pressure independently for pulsing each precursor.Appropriate temperatures and pressures may be maintained, whether theprecursor is a single precursor or a mixture of precursors.

In an embodiment, a number of indium oxide layers and a number oftitanium oxide layers may be formed by atomic layer deposition, wherethe number of titanium oxide layers is selected to be significantly lessthan the number of indium oxide layers. Then, the indium oxide layersand the titanium oxide layers may be annealed to form titanium-dopedindium oxide. In an embodiment, the number of titanium oxide layers isselected such that the percentage of titanium oxide in the total numberof indium oxide layers and titanium oxide layers is less than or equalto 7%. In an embodiment, the number of titanium oxide layers is selectedsuch that the atomic concentration of titanium in the formed Ti-dopedindium oxide is less than or equal to 7%. In an embodiment, the numberof titanium oxide layers may be interspersed among the number of indiumoxide layers in a predetermined arrangement prior to annealing. In anembodiment, the number of titanium oxide layers may be interspersedamong the number of indium oxide layers in a random order prior toannealing. In various embodiments, the order of forming InO_(x) andTiO_(y) layers may be permutated. The annealing may be conducted in anitrogen ambient. In an embodiment, annealing may be conducted in anitrogen ambient having a small amount of oxygen. However, annealing isnot limited to these ambient conditions. In an embodiment, annealing mayperformed at 550° C. or higher. In an embodiment, annealing mayperformed for about 60 minutes. Other annealing temperatures andannealing times may be used.

In an embodiment, a layer of indium oxide and a layer of titanium oxideare each grown by atomic layer deposition to a thickness such thatannealing these layers at appropriate temperatures essentially convertsthese layers to a layer of titanium-doped indium oxide. In the variousembodiments, the thickness of a titanium-doped indium oxide film isrelated to the number of ALD cycles performed and the growth rateassociated with forming each layer of InO_(x) and TiO_(y). In anembodiment, a Ti-doped InO film may be grown to a desired thickness byrepetition of a process including atomic layer deposition of layers ofInO_(x) and TiO_(y) followed by annealing. In an embodiment, a basethickness may be formed according to various embodiments such thatforming a predetermined thickness of a Ti-doped InO film may beconducted by forming a number of layers having the base thickness. Ascan be understood by one skilled in the art, determining the basethickness depends on the application and can be determined duringinitial processing without undue experimentation. Relative amounts ofindium, titanium, and oxygen in a Ti-doped InO film may be controlled byregulating the relative thicknesses of the individual layers of oxidesformed. In addition, relative amounts of indium, titanium, and oxygen ina Ti-doped InO film may be controlled by forming a layer of Ti-doped InOas multiple layers of different base thickness and by regulating therelative thicknesses of the individual layers of oxides formed in eachbase layer prior to annealing. Such regulation may be used to form anindium oxide layer having a selected titanium doping profile. The dopingprofile may include graded titanium doping decreasing away from thesubstrate on which the indium oxide layer is formed. The doping profilemay include graded titanium doping increasing away from the substrate onwhich the indium oxide layer is formed. The doping profile may includehaving the largest concentrations of titanium at the ends of the indiumoxide layer. The doping profile may include having the largestconcentrations of titanium in a middle region in the indium oxide layer.The titanium doping profile is not limited to these embodiments, but mayhave a profile selected for a given application. As can be understood bythose skilled in the art, particular effective growth rates for theengineered titanium-doped indium oxide film can be determined duringnormal initial testing of the ALD system used in processing atransparent conductive titanium-doped indium oxide for a givenapplication without undue experimentation.

In an alternative embodiment, an ALD cycle for forming Ti-doped InO mayinclude sequencing the component-containing precursors in variouspermutations. In an embodiment, an ALD cycle to form titanium-dopedindium oxide may include a number, x, of indium/oxygen sequences and anumber, y, of titanium/oxygen sequences. The number of sequences x and ymay be selected to engineer the relative amounts of indium, titanium,and oxygen. In an embodiment, the number of sequences x and y may beselected to form a titanium-doped indium oxide having a titaniumconcentration less than a predetermined amount. In an embodiment, thepredetermined amount is less than or equal to 7%. Such a process may beconducted as an ALD process in which a number of titanium/oxygen cyclesare substituted for indium/oxygen cycles in the formation of indiumoxide.

After repeating a selected number of ALD cycles, a determination may bemade as to whether the number of cycles equals a predetermined number toform the desired titanium-doped indium oxide layer. If the total numberof cycles to form the desired thickness has not been completed, a numberof cycles is repeated. The thickness of a titanium-doped indium oxidelayer formed by atomic layer deposition may be determined by a fixedgrowth rate for the pulsing periods and precursors used, set at a valuesuch as N nm/cycle, and the number of cycles conducted. Depending on theprecursors used for ALD formation of a Ti-doped InO film, the processmay be conducted in an ALD window, which is a range of temperatures inwhich the growth rate is substantially constant. If such an ALD windowis not available, the ALD process may be conducted at the same set oftemperatures for each ALD sequence in the process. For a desiredtitanium-doped indium oxide layer thickness, t, in an application, theALD process is repeated for t/N total cycles. Once the t/N cycles havecompleted, no further ALD processing for the titanium-doped indium oxidelayer may be required. A titanium-doped indium oxide layer processed atrelatively low temperatures associated with atomic layer deposition mayprovide an amorphous layer. In an embodiment, different ALD cycleshaving different numbers of indium sequences and titanium sequences maybe used to form an indium oxide layer with a selected titanium dopingprofile. Various titanium doping profiles may by constructed, asdiscussed above with respect to embodiments in which ALD indium oxidelayers and ALD titanium oxide layers are annealed to form a Ti-doped InOlayer.

FIG. 1A illustrates a representation of an embodiment of a flat paneldisplay 100 having a transparent conductive Ti-doped InO film as a TCO110. Flat panel display 100 may include a phosphor layer 120 separatedby a dielectric layer 130 from TCO layer 110 and separated by adielectric layer 140 from a conductive layer 150. Conductive layer 150may be a metal layer. TCO layer 110 and conductive layer 150 areconfigured to contact an appropriate voltage source, which enables avoltage, V_(APPLIED), to be applied between TCO layer 110 and conductivelayer 150. Various types or configurations of voltage sources may beused to provide V_(APPLIED). Dielectric layer 130 has a thickness 132,phosphor layer 120 has a thickness 122, and dielectric layer 140 has athickness 142.

FIG. 1B shows a circuit diagram of an embodiment representative of flatpanel display 100 of FIG. 1A. In this embodiment, the effective circuithas a capacitance, C_(P), associated with phosphor layer 120 and acapacitance, C_(D), associated both with dielectric layer 130 havingthickness 132 and dielectric layer 140 having thickness 142. Suchcapacitances C_(D) may be obtained using the same material with the samedimensions for both dielectric layer 130 and dielectric layer 140. Otherconfigurations may be used including having dielectric layer 130 anddielectric layer 140 with different capacitance values. FIG. 1C shows arepresentation of an energy diagram of an embodiment of flat paneldisplay 100 of FIG. 1A.

FIG. 2 illustrates a representation of an embodiment of an apparatus 200having a photovoltaic cell 220 contacting a transparent conductiveTi-doped InO film as a front-side TCO layer 210. Photovoltaic cell 220may have a multiple layer structure. In an example embodiment,photovoltaic cell 220 includes a CdS layer 224 and a CdTe layer 226.Photovoltaic 220 is not limited to these materials or layerconfigurations. In addition to having TCO layer 210 as a contact,photovoltaic cell 220 contacts a backside conductor 230. Backsideconductor 230 may be a metal layer. A transparent layer 240 may bedisposed on TCO layer 210. Transparent layer 240 may be a glass layer.

FIG. 3A illustrates a representation of a cross sectional view of alight emitting diode (LED) 320 having a transparent conductive Ti-dopedInO film as a TCO contact 310. FIG. 3B illustrates a representation of atop view of TCO contact 310 on a semiconductor surface 307 of FIG. 3A.Light emitting diode 320 includes a backside contact 330, which is usedwith TCO contact 310 to provide a potential to LED 320. LED 320 includesa n-type region 322 and a p-type region 324. N-type region may be an n+region. A transparent conductive Ti-doped InO film as a TCO contact isnot limited to the configuration of FIGS. 3A-3B, but may be used invarious configurations with various materials and doping levels for alight emitting diode. Further, a transparent conductive Ti-doped InOfilm may be used in any light emitting structure that has a contactlayer in which light generated in an underlying region is to betransmitted through the contact layer. A transparent conductive Ti-dopedInO film for a light emitting structure is not limited to an LED. Othersuch structures include semiconductor-based lasers.

FIG. 4 shows a representation of an embodiment of a transparentconductive Ti-doped InO layer as a low emissivity transparent conductiveoxide layer 410 of a smart window 400. A smart window is a window inwhich properties associated with the window may be controlled. Forexample, a smart window may be constructed such that the amount of lightpassing through the window may be regulated. TCO layer 410 is disposedon glass window 405. Glass window 405 may include any typical materialto be used as a window. Transparent conductive Ti-doped InO layer 410may be electrically controlled through contacts to TCO 410 layer tomodify the radiative emissivity of smart window 400. In an embodiment,transparent conductive Ti-doped InO layer 410 is adapted to give smartwindow 400 low emissivity to provide low heat loss 417. Embodiments of atransparent conductive Ti-doped InO layer as a low emissivity TCO layerfor a smart window are not limited to the configuration of FIG. 4.

FIG. 5 shows a representation of an embodiment of a transparentconductive Ti-doped InO layer as a TCO layer 510 to heat a smart window500. Smart window 500 includes TCO layer 510 on a layer of glass 505.TCO layer may be used as a resistive element to control heating of smartwindow 500. With no current flowing through TCO layer 510, smart window500 may operate as a conventional window. Embodiments of a transparentconductive Ti-doped InO layer to heat a smart window are not limited tothe configuration of FIG. 5.

FIG. 6 depicts a representation of an embodiment of a transparentconductive Ti-doped InO film as a TCO layer for an optical waveguidestructure 600. Optical waveguide structure 600 includes at least tworegions 620, 630, where region 620 has a different index or refractionthan region 630. Regions 620 and 630 are separated by a TCO layer 610containing transparent conductive Ti-doped InO. Layer 610 may haveshaped and have a thickness based on the application of the layer 610 inan optical waveguide configuration. In an embodiment, region 620 is acladding region having a high index of refraction and coating region 610is part of the optical waveguide region having a lower index ofrefraction. Region 630 is the core region where a guided wave isconstrained.

FIG. 7 depicts a representation of an embodiment of a transparentconductive Ti-doped InO film as a TCO layer for an optical waveguidestructure 700. Optical waveguide structure 700 includes a core layer720, a cladding layer 710, and a cladding layer 730 in which at leastone of cladding layer 710 and cladding layer 730 contains a layer oftransparent conductive Ti-doped InO. Core layer 720 is an optic layer.An optic layer is a layer used for propagation of light or used tomodify propagation of light. In an embodiment, with optical waveguidestructure 700 in a planar-like configuration cladding layer 710 andcladding layer 730 are different layers. In such a configuration, thematerial used in cladding layer 710 may be the same as the material usedin cladding layer 730. In such a configuration, the material used incladding layer 710 may be different from the material used in claddinglayer 730. In such a configuration, the material used in cladding layer710 may have an index of refraction different from the index ofrefraction of the material used in cladding layer 730, where bothindexes are less than the index of refraction for core layer 720. In anembodiment, with optical waveguide structure in a planar-likeconfiguration, optical waveguide structure 700 is not limited to a threelayer structure, but may have additional dependent on the application.Optical waveguide structures in a planar-like configuration are used inintegrated optics. In an embodiment, with optical waveguide structure ina cylindrical-like configuration, cladding layer 710 and cladding 730are the same layer. In such a cylindrical-like configuration, core layer720 and cladding layer 710/730 may have various shapes including but notlimited to, a circular outer surface and an elliptical outer surface.Optical waveguide structures in a cylindrical-like configuration includeoptical fibers.

In an embodiment, core layer 720 may be an electrooptic material whoseindex of refraction may be modified in the presence of an appliedpotential. With contacts applied to TCO cladding layers 710 and 730, TCOcladding layers 710 and 730 may be used to modulate the index ofrefraction of core layer 720. The material for electrooptic core layer720 may be selected such that for all modulations of an application, theindex of refraction of core layer 720 is maintained at a higher indexthan for cladding layers 710, 730.

FIG. 8 depicts a representation of an embodiment of an apparatus 800having a transparent conductive Ti-doped InO film as a TCO layer toprovide electrooptic modulation. In an embodiment, apparatus 800includes a substrate 805, a bottom cladding layer 820, a top claddinglayer 830, and a layer 840 of electrooptic material between bottomcladding layer 820 and a top cladding layer 830. Layer 840 ofelectrooptic material is an optical layer. Substrate 805 may be GaAs orother III-V composition. Cladding material may include silicon oxide orother appropriate dielectric material. Electrodes are provided tomodulate the optical properties of electrooptic material 840.Electrooptic material 840 may be modulated using a top TCO layer 810 anda bottom TCO layer 812. At least one of the TCO layers 810, 812 maycontain transparent conductive Ti-doped InO. In an embodiment, both TCOlayers 810, 812 contain transparent conductive Ti-doped InO. Thematerials selected for substrate 805, bottom cladding layer 820, topcladding layer 830, and layer 840 may be chosen based on thecharacteristics of the application, such as the wavelengths of interest.

FIG. 9 illustrates a block diagram for a system 900 having one or moredevices having a structure including a transparent conductive Ti-dopedInO film. The Ti-doped InO TCO layer may be structured as one or moremonolayers, where the thickness of the Ti-doped InO TCO layer may rangefrom a monolayer to thousands of angstroms or more. The Ti-doped InO TCOfilm may be processed using atomic layer deposition. Electronic system900 includes a controller 905, a bus 915, and a device 925, where bus915 provides electrical conductivity between controller 905 and device925. In various embodiments, device 925 may include an embodiment of atransparent conductive Ti-doped InO film. System 900 may include, but isnot limited to, fiber optic systems, electro-optic systems, informationhandling systems, and systems having smart windows.

FIG. 10 shows a block diagram of an embodiment of a system 1000 having acontroller 1005 coupled to various devices, in which at least one devicecontains a transparent conductive Ti-doped InO film. System 1000 mayinclude a memory 1025, an apparatus 1035, and a bus 1015, where bus 1015provides electrical conductivity between controller 1005 and apparatus1035 and between controller 1005 and memory 1025. Bus 1015 may includean address bus, a data bus, and a control bus, each independentlyconfigured. Alternatively, bus 1015 may use common conductive lines forproviding one or more of address, data, or control, the use of which isregulated by controller 1005. In an embodiment, apparatus 1035 mayinclude a transparent conductive Ti-doped InO_(x) film. Apparatus 1035may be configured as a flat-panel display, a photovoltaic cell, a smartwindow, a light emitting diode, light emitting diode array, a lightgenerating device, an optical waveguide, or other apparatus arranged touse a transparent conductive Ti-doped InO_(x) film. An embodiment mayinclude an additional peripheral device or devices 1045 coupled to bus1015. Peripheral devices 1045 may include displays, additional storagememory, or other control devices that may operate in conjunction withcontroller 1005. Alternatively, peripheral devices 1045 may includedisplays, additional storage memory, or other control devices that mayoperate in conjunction with memory 1025, or controller 1005 and memory1025. Peripheral devices 1045 may include other devices having atransparent conductive Ti-doped InO_(x) film.

In an embodiment, controller 1005 is a processor. Memory 1025 may berealized as various types of memory devices. It will be understood thatembodiments are equally applicable to any size and type of memorycircuit and are not intended to be limited to a particular type ofmemory device. Memory types include a DRAM, SRAM (Static Random AccessMemory) or Flash memories. Additionally, the DRAM could be a synchronousDRAM commonly referred to as SGRAM (Synchronous Graphics Random AccessMemory), SDRAM (Synchronous Dynamic Random Access Memory), SDRAM II, andDDR SDRAM (Double Data Rate SDRAM), as well as other emerging DRAMtechnologies. System 1000 may include, but is not limited to, fiberoptic systems, electro-optic systems, information handling systems, andsystems having smart windows.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is calculated to achieve the same purpose maybe substituted for the specific embodiments shown. It is to beunderstood that the above description is intended to be illustrative,and not restrictive, and that the phraseology or terminology employedherein is for the purpose of description and not of limitation.Combinations of the above embodiments and other embodiments will beapparent to those of skill in the art upon studying the abovedescription.

What is claimed is:
 1. A method comprising: forming indium oxide by amonolayer or partial monolayer sequencing processing; and doping theindium oxide with titanium, forming a transparent conductivetitanium-doped indium oxide.
 2. The method of claim 1, wherein formingthe transparent conductive titanium-doped indium oxide includes formingthe transparent conductive titanium-doped indium oxide with a titaniumatomic concentration less than or equal to 7%.
 3. The method of claim 1,wherein forming the transparent conductive titanium-doped indium oxideincludes forming the transparent conductive titanium-doped indium oxidewith an atomic concentration of titanium ranging from 1% to 3%.
 4. Themethod of claim 1, wherein the method includes forming the conductivetitanium-doped indium oxide in a flat-panel display.
 5. The method ofclaim 1, wherein the method includes forming the transparent conductivetitanium-doped indium oxide in a photovoltaic cell.
 6. The method ofclaim 1, wherein the method includes forming the transparent conductivetitanium-doped indium oxide in a smart window.
 7. The method of claim 1,wherein the method includes forming the transparent conductivetitanium-doped indium oxide in a light emitting diode array.
 8. Themethod of claim 1, wherein the method includes forming the transparentconductive titanium-doped indium oxide in an optical waveguide.
 9. Themethod of claim 1, wherein the doping the indium oxide with titaniumincludes using a titanium precursor that contains oxygen.
 10. A methodcomprising: forming indium oxide by a monolayer or partial monolayersequencing process; and providing titanium for the indium oxide by themonolayer or partial monolayer sequencing process; and controllingindium sequences and titanium sequences in a number of cycles of themonolayer or partial monolayer sequencing process such that the indiumoxide is doped with titanium, forming a transparent conductivetitanium-doped indium oxide.
 11. The method of claim 10, whereincontrolling indium sequences and titanium sequences includes performingdifferent cycles of the monolayer or partial monolayer sequencingprocess having different numbers of indium sequences and titaniumsequences to form the transparent conductive titanium-doped indiumoxide.
 12. The method of claim 10, wherein the method includescontrolling the indium sequences and the titanium sequences such thatthe titanium of the transparent conductive titanium-doped indium oxidehas a graded titanium doping profile.
 13. The method of claim 12,wherein the graded titanium doping profile includes a concentration oftitanium at a first end of a region containing the transparentconductive titanium-doped indium oxide and at a second end distal fromthe first end that is larger than a titanium concentration in the regionbetween the first end and the second end.
 14. The method of claim 12,wherein the graded titanium doping profile includes titanium decreasingaway from a substrate on which the transparent conductive titanium-dopedindium oxide is formed.
 15. The method of claim 12, wherein the gradedtitanium doping profile includes titanium increasing away from asubstrate on which the transparent conductive titanium-doped indiumoxide is formed.
 16. A method comprising: forming indium oxide by amonolayer or partial monolayer sequencing processing; forming titaniumoxide by the monolayer or partial monolayer sequencing processing; andprocessing the formed indium oxide and the formed titanium oxide suchthat the indium oxide is doped with titanium, forming a transparentconductive titanium-doped indium oxide.
 17. The method of claim 16,wherein processing the formed indium oxide and the formed titanium oxideincludes annealing the indium oxide and the titanium oxide convertingthe indium oxide and the titanium oxide to transparent conductivetitanium-doped indium oxide.
 18. The method of claim 16, wherein themethod includes forming a base thickness of the transparent conductivetitanium-doped indium oxide and repeating forming the base thicknessuntil a desired thickness of transparent conductive titanium-dopedindium oxide is formed.
 19. The method of claim 16, wherein processingthe formed indium oxide and the formed titanium oxide includesregulating relative thicknesses of individual layers of formed indiumoxide and formed titanium oxide and annealing the formed individuallayers to convert the formed indium oxide and formed titanium oxide totransparent conductive titanium-doped indium oxide.
 20. The method ofclaim 19, wherein processing the formed indium oxide and the formedtitanium oxide includes using the regulation such that transparentconductive titanium-doped indium oxide having a selected titanium dopingprofile is formed.